Nowadays, fluid transportation devices used in many sectors such as pharmaceutical industries, computer techniques, printing industries, energy industries are developed toward miniaturization. The fluid transportation devices are used in for example micro pumps, micro atomizers, printheads or industrial printers for transporting small amounts of gases or liquids. Therefore, it is important to provide an improved structure of the fluid transportation device.
FIG. 1A is a schematic front exploded view illustrating a conventional fluid transportation device. FIG. 1B is a schematic rear exploded view illustrating the conventional fluid transportation device of FIG. 1A. As shown in FIGS. 1A and 1B, the conventional fluid transportation device 1 comprises a valve seat 10, a valve membrane 11, a valve cap 12, an actuating module 13, and a cover plate 14. For assembling the conventional fluid transportation device 1, the valve membrane 11 is firstly arranged between the valve seat 10 and the valve cap 12. Then, the valve membrane 11, the valve seat 10 and the valve cap 12 are laminated together. Then, the actuating module 13 is disposed on a corresponding position of the valve cap 12. The actuating module 13 comprises a vibration film 131 and an actuator 132 for actuating the fluid transportation device 1. Afterwards, the cover plate 14 is disposed on the actuating module 13. Meanwhile, the conventional fluid transportation device 1 is assembled.
As shown in FIG. 1A, the valve seat 10 comprises an inlet channel 101 and an outlet channel 102. The ambient fluid is introduced into the inlet channel 101 and then transported to an opening 103 in a top surface of the valve seat 10. An outlet buffer cavity 104 is formed between the valve membrane 11 and the valve seat 10 for temporarily storing the fluid therein. The fluid contained in the outlet buffer cavity 104 is transported to the outlet channel 102 through another opening 105 and then exhausted out of the valve seat 10 from the outlet channel 102. Moreover, the valve membrane 11 has an inlet valve structure 111 and an outlet valve structure 112, which are respectively aligned with the opening 103 and the opening 105.
The valve cap 12 comprises an inlet valve channel 122 and an outlet valve channel 123, which are respectively aligned with the inlet valve structure 111 and the outlet valve structure 112. Moreover, an inlet buffer cavity 124 (see FIG. 1B) is formed between the valve membrane 11 and the valve cap 12. Corresponding to the actuator 132 of the actuating module 13, a pressure cavity 126 is formed in the top surface of the valve cap 12. The pressure cavity 126 is in communication with the inlet buffer cavity 124 through the inlet valve channel 122. The pressure cavity 126 is also in communication with the outlet valve channel 123.
Please refer to FIGS. 1B, 1C, 1D and 1E. A raised structure 125 is formed at the periphery of the outlet valve channel 123 corresponding to the bottom surface 121 of the valve cap 12 of the conventional fluid transportation device 1. The raised structure 125 is sustained against the outlet valve structure 112 so as to provide a pre-force to the outlet valve structure 112. When the inlet valve structure 111 is opened and the fluid is introduced within the valve cap 12 (see FIG. 1D), the volume of the pressure cavity 126 is expanded to result in suction of the valve membrane 11. Since the raised structure 125 of the valve cap 12 provides the pre-force to the outlet valve structure 112, the raised structure 125 results in a pre-sealing effect to prevent backflow. Moreover, since a negative pressure difference in the pressure cavity 126 causes a shift of the inlet valve structure 111, the fluid is flowed from the valve seat 10 into the inlet buffer cavity 124 through the inlet valve structure 111, and then transmitted to the pressure cavity 126 through the inlet buffer cavity 124 and the inlet valve channel 122. Under this circumstance, the inlet valve structure 111 is quickly opened or closed in response to the positive or negative pressure difference in the pressure cavity 126, so that the fluid is controlled to flow through the fluid transportation device without being returning back to the valve seat 10.
The valve seat 10 has another raised structure 106, which is sustained against the inlet valve structure 111. The raised structure 106 and the raised structure 125 are protruded in opposite directions. If the volume of the pressure cavity 126 is shrunken to result in an impulse (see FIG. 1E), the raised structure 106 on the top surface of the valve seat 10 will provide a pre-force to the inlet valve structure 111. The pre-force results in a pre-sealing effect to prevent backflow. Moreover, since a positive pressure difference in the pressure cavity 126 causes a shift of the outlet valve structure 112, the fluid is flowed from the pressure cavity 126 into the output buffer cavity 104 of the valve seat 10 through the valve cap 12, and exhausted out of the fluid transportation device 1 through the opening 105 and the outlet channel 102. Under this circumstance, the outlet valve structure 112 is opened to drain out the fluid contained in the pressure cavity 126 so as to transport the fluid.
In the conventional fluid transportation device 1, the actuating module 13 is enabled to expand or shrink the volume of the pressure cavity 126 to result in a pressure difference. Due to the pressure difference, the fluid is introduced into the pressure cavity 126 through the inlet valve structure 111 or ejected out of the pressure cavity 126 through the outlet valve structure 112. The way of actuating the conventional fluid transportation device 1, however, still has some drawbacks. For example, the operations of the inlet valve structure 111 and the outlet valve structure 112 are usually unstable. Especially when the inlet valve structure 111 is repeatedly actuated at the high frequency and the fluid is an irregular turbulent fluid, the regular motion of the inlet valve structure 111 is disturbed.
Moreover, since the fluid transportation is driven by expanding or shrinking the volume of the pressure cavity, the flowing efficiency is usually unsatisfied. As shown in FIG. 1D, after the fluid is introduced into the inlet valve channel 122 through the inlet valve structure 111, the fluid will be directed to the pressure cavity 126 in diverse directions. In other words, a portion of the fluid may be flowed to the position distant from the outlet. Under this circumstance, since the fluid is partially stagnant, the performance of the conventional fluid transportation device 1 is deteriorated.
Therefore, there is a need of providing a fluid transportation device for increasing the stable operations of the valve structure and enhancing the flowing efficiency in order to obviate the drawbacks encountered from the prior art.